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Brake upgrade for my 98 K3500
- Thread starter M.Kasperan
- Start date
handcannon
Well-Known Member
I'd send them air freight, but my throwing arm is out of shape.
Back on the serious side,
Earlier you said you were checking out the possible need to change to the newer, larger MC. What did you find out?
Leroy, my drill press doesn't turn CCW, but I also re-checked that web site and it sure looks to me like the reamer is for CW rotation.
The more I think about this, the more exited I get about the possibility of having better brakes. My current plan is to be the first person through the gate at the pick-n-pull Monday morning. I've been back there twice now too, first to double check the tie rod situation, second (today) to preplan what I'll need for tools.
Don
M.Kasperan
Member
As of now I haven't done anything about the MC. If the 2500hd MC has a bigger bore I would change to it. I pedal is good but not right at the top where I think it should be.
Most air drills are CW rotation. Can you confirm?
M.Kasperan
Member
Yes normal rotation. Clock wise.
handcannon
Well-Known Member
The 2500HD does have a bigger bore. My 94, and I think your 98, has a 1 1/4" bore. The 2500 is a metric size, which works out to 1.46". Somewhere in the last few days I read that the smaller stock bore will go farther down when stepping on the pedal before coming up solid on the brakes. And when the larger bore is put in place of the smaller the pedal will stay higher and firmer when stepped on. I can't remember now where I read that though, so I have been unable to find it again.
My big question, one that I haven't checked out yet, will the larger 2500HD MC fit in place of the smaller MC?
Don
My big question, one that I haven't checked out yet, will the larger 2500HD MC fit in place of the smaller MC?
Don
- Staff
- #27
Also keep in mind that teh larger MC will give lower pressure to your brakes for the same amount of pedal pressure. Yes it will move more fluid, but at less pressure. it shouldn't be to big of an issue though since the rear drums are maxxed out at 800 PSI in the proportioning valve whereas teh front brakes I would imagine could easily hit 3K PSI with the smaller bore MC. The newer style brakes use less pressure, more volume, and alot more surface area to achieve the better braking. Mine with my current set-up works pretty good, and is ALOT better than what it was stock. I have RUSSEL stainless braided brake lines front and rear, RAYBESTOS advanced technology metalic brake pads, RAYBESTOS HD premium rotors, and the AC DELCO DURASTOP rear shoes.
Thank you. As it is CW I "might" have access to a cheaper $ tool, let me check on Monday. And Ferm that reminds me I forgot to check a price on that one way check valve for you. Will do that tomorrow also.
handcannon
Well-Known Member
]\
Today I had a chance to compare my MC to the MC on my brothers 03 3/4T 4X4 Chev. I tried getting my calipers in there to measure the distance between bolts and as near as I can tell they are a match. The big question is if the part of the MC that goes into the end of the hydrobooster and the push rod are the same. Since everything else matches up I'm leaning towards all that matching up also.
Ferm, are you saying that the lower pressure generated by the newer, larger bore MC is good or bad? I'm thinking you're saying that it is not bad, leaning towards the better side maybe?
Don
OK just confirmed the reamer is a "lefthand spiral" the cutting edge is on right. The reamer turns CW and pushes the spoils down instead of up like a drill bit will do. This is so the tool will ream and not tend to try to drill into the piece.
- Staff
- #31
It should work fine. Basically GM upped amount of piston area to put pressure onto the pads by adding the extra piston, but offset it by going to a larger MC piston. The increase in braking comes from all the added pad area that the newer trucks have. Also since the newer trucks have 4 wheel disc brakes, they have more rubber brake lines so this is probably another reason for GM wanting to go to lower braking system pressure. I believe the newer MC and front brake set-up will work fine, but you will have to push on teh pedal harder to get the same amount of rear braking.
M.Kasperan
Member
I was not asking but rather telling. No question marks in my post. 
handcannon
Well-Known Member
I just spent some time out at the pick-n-pulls today and pulled spindles from an 02 DMax for a brake upgrade like M.Kasperan did.
My question about whether the newer, larger MC would fit on the older hydroboost is answered, no it won't. The older MC has a nose, that fits into the hydro, of about 1 1/2" diameter ( didn't write down this info, having to trust my memory which is scary!!). The newer MC has a nose of about 1 13/16ths", so it's a substantial difference.
Sooo, in order to get the newer MC on the older trucks the newer hydro has to be installed along with the newer MC. BUT, there is a problem there also. The newer hydro has a different bolt pattern where it bolts to the firewall.
I went ahead and got a newer hydro and master so I could see what could be done to make them work in the older trucks.
I didn't have time to pull an older hydro to compare to the newer hydro, but after doing what I could to do some comparison measurements, I think there may be a work-around for that problem. I turned myself on my head and spent some time looking under the dash of an older and a newer truck.
The nose of the hydro that goes through the firewall appears to be the same between the older and newer style hydros. Both have removable mounting plates that have the mounting studs welded onto it. I'm thinking that the firewall mounting plates can be interchanged. Sometime later this week I'll spend some more time at a pick-n-pull and get an older style hydro so I can find out for sure if the newer hydro can be easily made to work in place of the older style hydro.
Don
My question about whether the newer, larger MC would fit on the older hydroboost is answered, no it won't. The older MC has a nose, that fits into the hydro, of about 1 1/2" diameter ( didn't write down this info, having to trust my memory which is scary!!). The newer MC has a nose of about 1 13/16ths", so it's a substantial difference.
Sooo, in order to get the newer MC on the older trucks the newer hydro has to be installed along with the newer MC. BUT, there is a problem there also. The newer hydro has a different bolt pattern where it bolts to the firewall.
I went ahead and got a newer hydro and master so I could see what could be done to make them work in the older trucks.
I didn't have time to pull an older hydro to compare to the newer hydro, but after doing what I could to do some comparison measurements, I think there may be a work-around for that problem. I turned myself on my head and spent some time looking under the dash of an older and a newer truck.
The nose of the hydro that goes through the firewall appears to be the same between the older and newer style hydros. Both have removable mounting plates that have the mounting studs welded onto it. I'm thinking that the firewall mounting plates can be interchanged. Sometime later this week I'll spend some more time at a pick-n-pull and get an older style hydro so I can find out for sure if the newer hydro can be easily made to work in place of the older style hydro.
Don
handcannon
Well-Known Member
Thanks for this info!
I'm forging ahead with this project, hoping for better brakes. I'm hoping all this isn't going to get too expensive for my very limited resources.
Something I just thought about, residual valve for the rear drum brakes. I'm going to have to find out where GM put the residual valve for the rear drums.
Don
handcannon
Well-Known Member
This sounds good, especially for use in a drill press where the quill is hand operated. No worries about the thing getting out of hand and suddenly boring itself too deep.
From what you previously posted I'm taking that this is the less expensive reamer that you may have access to. I'm interested in more info if this is so.
Don
No I was refering to the $127 one.
Also, Ive done a few HydroBoost convertions on other vehicles and the mounting plate is removeable (on the old ones anyway) I posted a trick to get the big nut off the back in my Suburban/isuzu swap thread.
- Staff
- #38
Theres no residual valve that I know of in the brake system. Residual valves are normally only used when the master cylinder is mounted lower than the brakes to prevent the fluid from draining back into the master and allowing air into the system. When the master cylinder is mounted higher than the brakes theer is no need for it. As for the proportioning valve, it is part of the ABS pump.
handcannon
Well-Known Member
Good to know that. Unless I find any info to the contrary I'll proceed without being concerned about any residual valve.
I'm just going by my experience with the older Toyota Landcruisers. They all had 10 lb residual valves built into the MC on the drum brake systems. They are very touchy about brake adjustment, and without a residual valve somewhere in line other people have had problems. The brake springs retract the shoes too far and cause problems with needing to have the shoes adjusted up extremely tight, or needing double pumps to get good pedal feel. I've changed my FJ40 over to 4 wheel discs to get away from the frequent manual adjustments required.
Don
I'm just going by my experience with the older Toyota Landcruisers. They all had 10 lb residual valves built into the MC on the drum brake systems. They are very touchy about brake adjustment, and without a residual valve somewhere in line other people have had problems. The brake springs retract the shoes too far and cause problems with needing to have the shoes adjusted up extremely tight, or needing double pumps to get good pedal feel. I've changed my FJ40 over to 4 wheel discs to get away from the frequent manual adjustments required.
Don
Big T
Well-Known Member
I too am very interested in this conversion project, but I'm having trouble visualizing what you're describing. So I have some questions:
1) Are you using and modifying the steering knuckles from the '98? Photos with arrows pointing to the mods would be extremely helpful.
2) When you say "spindle" I think axle spindle such as on a 2wd and I'm thus at a loss as to what the mod would be there. I see a 4wd axle in your photos, so I know this must be wrong. Is the spindle you're referring to on the steering knuckle and receives the ball joint?
3) I at a loss as to your mods on the tie rod: "cut the ball joint end off the turned them down and retreaded them to fit the 2500hd outer tierod. So what you end up with is a threaded rod that fits the stock adjuster on one end and the 2500hd tierod on the other." It would be great if you could provide photos with arrows pointing to the mods here.